Synonym(s): Protein-glutamine gamma-glutamyltransferase, Fibrinoligase, TGase
Transglutaminases catalyse the post-translational modification of proteins at glutamine residues, with formation of isopeptide bonds. Members of the transglutaminase family usually have three domains: N-terminal , middle and C-terminal. The middle domain is usually well conserved, but family members can display major differences in their N- and C-terminal domains, although their overall structure is conserved . This entry represents the C-terminal domain found in transglutaminases, which consists of an immunoglobulin-like beta-sandwich consisting of seven strands in two sheets with a Greek key topology.
The best known transglutaminase is blood coagulation factor XIII, a plasma tetrameric protein composed of two catalytic A subunits and two non-catalytic B subunits. Factor XIII is responsible for cross-linking fibrin chains, thus stabilizing the fibrin clot. Protein-glutamine gamma-glutamyltransferases are calcium-dependent enzymes that catalyse the cross-linking of proteins by promoting the formation of isopeptide bonds between the gamma-carboxyl group of a glutamine in one polypeptide chain and the epsilon-amino group of a lysine in a second polypeptide chain. TGases also catalyse the conjugation of polyamines to proteins [1683845, 1974250].